The invention relates to the field of mixing fluids, where one fluid is at a very low pressure and one fluid is at a very high pressure, and to use such fluid mixing to increase the megawatt output of a steam power plant, with a reduction of fuel consumption, by incorporating a newly modified mechanical system that is able to evacuate gas from very low pressures, and to recompress the gas to very high pressures.
In my U.S. Pat. Nos. 5,255,519 and 5,444,981 (incorporated herein by reference), I proposed increasing the efficiency in the generation of power, particularly electric power, using the Rankine cycle, by incorporating a light gas in the working fluid to increase the compressibility of the working fluid, and hence the expansion of the fluid in the cycle. In the closed system disclosed in those patents, a light, condensable gas, typically helium, is added to a working fluid, typically water, in a boiler. The working fluid is vaporized in the boiler, and the mixture of light gas and vaporized working fluid is used to operate a turbine to generate electric power. The light gas and working fluid mixture is then passed to a condenser to separate the working fluid from the light condensable gas, and the gas and working fluid are separately returned to the boiler. I refer to this system for increasing efficiency of the Rankine cycle as the “KaKovitch Cycle.”
The addition of the light gas to the system creates a thermodynamic cycle parallel to the Rankine cycle, using the light gas as the working fluid, in contrast to the Rankine cycle, which uses steam as the working fluid. The two cycles are integrated to jointly convert heat energy to mechanical energy with greater efficiency. The combination of steam and helium creates a working fluid of increased compressibility factor-Z.
The amount of usable energy in an power plant using the Rankine cycle is defined primarily by enthalpy. The difference between ideal and actual enthalpy of the system is tied to the residual enthalpy of that system (enthalpy departure). The combination of the parallel Rankine and helium cycles into a new combined cycle substantially increases the amount of work done by the new working fluid, as compared with steam alone, for the same amount of fuel consumed. This decrease in the consumption of fuel has the added benefit of reduction of the emission of greenhouse gases creates eligibility for carbon credit programs.
The parallel helium cycle can be retrofitted into an existing power plant, or incorporated into the design of new power plants. In either case, it is required that a light gas at a very low pressure be incorporated into a working fluid at a very high pressure.
In the combined helium-steam cycle, a portion of the light gas may be returned to the boiler by way of aspiration by the working fluid or may be returned separately. Additionally, a compressor may be used to return the light gas to the boiler at high pressure.
In my U.S. Pat. No. 5,810,564 (incorporated herein by reference), I proposed the use of an apparatus described as a “vortex pump” to evacuate helium from the condenser and to return the separated helium to the boiler. Because the helium is returned to the boiler, however, the efficiency of the mixing of the helium with the working fluid is limited. Greater efficiency would be expected by mixing the helium with the compressed working fluid before heating in the boiler, but this presents problems, since the compressed working fluid is at a very high pressure, possibly in the range of 2000-4000 psig, while the helium is at a very low pressure, which makes mixing difficult.
Another such device for mixing fluids is disclosed in my U.S. Pat. No. 6,358,015, also incorporated herein by reference.